I'm at 120,000 miles on my 2010 S40 and am quite confused about what exactly needs to be replaced as far as belts and tensioners go.

I know the timing belt, tensioner, and idler pulleys need replaced.

There are two serpentine belts that I know also need replaced. The confusion is about whether or not any tensioners or pulleys should be replaced at that time. The dealer says no, however when I look up online it says: "replace auxillary belt, tensioner, and pulley." FCP Euro sells a kit with both belts and two tensioners, but no pulley.

If anyone has any insight that would be great, thanks!

 

Replacing the belts as preventative maintenance is awesome. I don't do that for mine. Replacing anything else before failure? To me it depends on your situation. If mine fails I can replace it on the side of the road normally. However, in some places that might be impossible due to extreme cold. The tensioner will have it's own pulley.

 

Unless really strapped for $$, I'd replace the tensioner. It has a bearing that does wear. Since the serpentine belts have to be removed, I recommend replacing them along with idler and tensioners. There have been reported cased on these cars where the serpentine belt snapps and fouls the timing belt, causing it to fail.

Many shops replacing the water pump when doing the timing belt. Volvo service usually recommends waiting until the 2nd timing belt change to do the pump unless it is leaking or has bearing noise.